Autism spectrum disorders (ASD) is diagnosed four times more often in boys than in girls with some studies putting this number much higher - maybe 10 or 15 times more common in males than females. Researchers aren't sure if this is because males simply have more of a tendency toward autism, the diagnostic criteria is skewed toward male behavior or if autism shows up differently in females and doctors are overlooking the symptoms.
One theory explores the idea that girls have some type of protection against ASD, possibly hormone levels in-utero that turn off autism genes. Or, because girls tend to have better overall social skills than boys, it is possible that the degree of autism needs to be higher for it to be seen. This theory may explain the observation that, although girls are not diagnosed with ASD as often, when they are they have a higher degree of difficulties. Those with mild ASD symptoms are better able to compensate for or hide the symptoms.
Some of the specific differences seen between males and females with ASD include:
- Girls with ASD tend to have more learning disabilities and struggle more academically.
- Girls with special interests tend to focus on more mainstream passions - such as ponies, dolls, princesses or drawing - things that neurotypical girls are also interested in. Boys, on the other hand, may have nontypical interests, for example, one boy with ASD was fascinated with washing machines and spent most of his time researching different types of washing machines.
- Boys with autism often have more repetitive behaviors, such as rocking back and forth or spinning an object. Girls tend to participate in these types of activities much less often.
In one research study women with autism scored similar to men in facial emotion recognition, however, on tasks involving attention to detail or dexterity requiring strategic thinking, the women with ASD scored similar to women without ASD and the men with ASD had more difficulty with the tasks.
Societal expectations may contribute to young girls with both parents and doctors overlooking the possibility of autism. Instead, young girls may be seen as shy or diagnosed with anxiety. Society sees it as more acceptable for little girls to be shy. Boys, on the other hand, are expected to be outgoing and active. When they are not, it is much more noticeable.
When girls are diagnosed, it is frequently much later - during the middle school and high school years when social skills become so important. Young girls who could memorize and "fake" social skills, such as smile and nod when someone is talking to you, find it much harder to navigate complicated teenage social interactions. They begin to stand out as being different.
Slowly, this may begin to change. According to Judith Gould, psychologist and director of the Lorna Wing Centre of the National Autistic Society (UK), "we are definitely seeing an increase in women and girls being diagnosed."  As research continues and more doctors and parents become aware of how autism shows up in females, more will be diagnosed and treated early, which is so important for those with autism.
"Cognition in Males and Females with Autism: Similarities and Differences," 2102, Oct., Meng-Chuan Lai et al, PLOS-One
"How Girls and Boys Differ When it Comes to Autism," 2012, April 4, Peter Szatmari, CNN.com
 "Why Autism is Different for Girls," 2010,